fputc

, putc

, putc_unlocked

, putchar

, putchar_unlocked

, putw

Synopsis

#include <stdio.h>
intfputc(intc, FILE *stream);

intputc(intc, FILE *stream);

intputc_unlocked(intc, FILE *stream);

intputchar(intc);

intputchar_unlocked(intc);

intputw(intw, FILE *stream);

Description

The fputc() function writes the byte specified by c (converted to an
unsigned char) to the output stream pointed to by stream, at the position
indicated by the associated file-position indicator for the stream (if defined), and advances
the indicator appropriately. If the file cannot support positioning requests, or if
the stream was opened with append mode, the byte is appended to
the output stream.

The st_ctime and st_mtime fields of the file will be marked for
update between the successful execution of fputc() and the next successful completion
of a call to fflush(3C) or fclose(3C) on the same stream or
a call to exit(3C) or abort(3C).

The putc() routine behaves like fputc(), except that it is implemented as
a macro. It runs faster than fputc(), but it takes up more
space per invocation and its name cannot be passed as an argument
to a function call.

The call putchar(c) is equivalent to putc(c, stdout). The putchar() routine is implemented
as a macro.

The putc_unlocked() and putchar_unlocked() routines are variants of putc() and putchar(), respectively,
that do not lock the stream. It is the caller's responsibility
to acquire the stream lock before calling these routines and releasing the lock
afterwards; see flockfile(3C) and stdio(3C). These routines are implemented as macros.

The putw() function writes the word (that is, type int) w to
the output stream (at the position at which the file offset, if
defined, is pointing). The size of a word is the size of
a type int and varies from machine to machine. The putw() function
neither assumes nor causes special alignment in the file.

The st_ctime and st_mtime fields of the file will be marked for
update between the successful execution of putw() and the next successful completion
of a call to fflush(3C) or fclose(3C) on the same stream or
a call to exit(3C) or abort(3C).

Return Values

Upon successful completion, fputc(), putc(), putc_unlocked(), putchar(), and putchar_unlocked() return the value
that was written. Otherwise, these functions return EOF, the error indicator
for the stream is set, and errno is set to indicate the error.

Upon successful completion, putw() returns 0. Otherwise, it returns a non-zero value,
sets the error indicator for the associated stream, and sets errno to
indicate the error.

An unsuccessful completion will occur, for example, if the file associated with
stream is not open for writing or if the output file cannot
grow.

Errors

The fputc(), putc(), putc_unlocked(), putchar(), putchar_unlocked(), and putw() functions will fail if
either the stream is unbuffered or the stream's buffer needs to be
flushed, and:

EAGAIN

The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the write operation.

EBADF

The file descriptor underlying stream is not a valid file descriptor open for writing.

EFBIG

An attempt was made to write to a file that exceeds the maximum file size or the process' file size limit.

EFBIG

The file is a regular file and an attempt was made to write at or beyond the offset maximum.

EINTR

The write operation was terminated due to the receipt of a signal, and no data was transferred.

EIO

A physical I/O error has occurred, or the process is a member of a background process group attempting to write to its controlling terminal, TOSTOP is set, the process is neither ignoring nor blocking SIGTTOU and the process group of the process is orphaned. This error may also be returned under implementation-dependent conditions.

ENOSPC

There was no free space remaining on the device containing the file.

EPIPE

An attempt is made to write to a pipe or FIFO that is not open for reading by any process. A SIGPIPE signal will also be sent to the calling thread.

A request was made of a non-existent device, or the request was outside the capabilities of the device.

Usage

Functions exist for the putc(), putc_unlocked(), putchar(), and putchar_unlocked() macros. To get
the function form, the macro name must be undefined (for example, #undef putc).

When the macro forms are used, putc() and putc_unlocked() evaluate the stream
argument more than once. In particular, putc(c, *f++); does not work sensibly. The
fputc() function should be used instead when evaluating the stream argument has
side effects.

Because of possible differences in word length and byte ordering, files written
using putw() are implementation-dependent, and possibly cannot be read using getw(3C) by
a different application or by the same application running in a different
environment.

The putw() function is inherently byte stream oriented and is not tenable
in the context of either multibyte character streams or wide-character streams. Application
programmers are encouraged to use one of the character-based output functions instead.